High-Performance Energy-Efficient Gas Heating Systems
Natural gas heating systems provide air from the registers at a
temperature range that is significantly higher than normal body
temperatures, so your home will feel warm and comfortable. Electric
heat pumps provide air from the registers at a temperature range
that is near - or sometimes below - body temperatures, which by
comparison feels cool.
Natural gas heating systems allow you to heat only the rooms you
choose. You can close off and not heat unused rooms in your home
which saves money. Thermostats can be set back by 10 degrees at
night, which can save you up to 10 percent on your annual heating
bills. New high-efficiency gas heating systems provide you with the
most economical, dependable and comfortable home heating.
Factors to Consider with Natural Gas
Below please find answers to some commonly asked questions about
natural gas furnaces. Should you have further questions,
please feel free to contact one of our three office
locations. We are happy to help.
Q. What terms should I know when choosing a new gas
furnace?
A. Annual Fuel Utilization
Efficiency (AFUE)- AFUE measures average annual seasonal
efficiency of a gas furnace or boiler and may be expressed as total
heating output divided by total energy (fuel) input. AFUEs for
furnaces can range from 57 to 97 percent.
Automatic Vent Damper- A
device installed in the venting system after the draft hood of an
applicance that automatically closes the vent when the furnace or
boiler is off and restricts heated air from going up the
vent.
Energy Savings Payback
(ESP)- The time needed to recover the investment on a
conservation measure through the resulting savings on fuel.
Flue Gases- The normal
products of the combustion process are carbon dioxide and water
vapor which are vented into the outdoor atmosphere.
Forced Draft System- A
mechanical system that moves the flue gases through the appliance
and creates more efficient heat transfer in the heat
exchanger.
Heat Exchanger- A section
of the furnace or boiler where the heat generated by the combustion
process is transferred to the circulating air or water.
Intermittent Ignition Device
(IID) - Use of a spark or other source of ignition as
opposed to a continuously burning pilot flame.
Secondary Heat Exchanger -
An additional heat exchanger through which hot flue gases pass
after leaving the conventional heat exchanger-resulting in greater
efficiency.
Through-the-Wall Vent - A
heating system that allows furnaces to be vented directly through
the wall.
Q. How can I determine the proper size furnace for my
home?
A. The size of the furnace or boiler refers to the heating
capacity rather than the physical dimensions. The correct furnace
or boiler sizing is determined by the size, use and construction of
the house, and the normal winter temperatures in the particular
area of the country. A qualified gas heating contractor should
evaluate the specific needs of your home. The new equipment can
then be sized correctly.
Q. What are the different gas heating systems available?
A. Conventional Warm Air
Furnace- A gas burner provides heat to the heat exchanger
which transfers the heat to the air that is then circulated by a
blower through ducts back to the furnace through return ducts to be
reheated. Equipped with standing gas pilots and draft hoods with
AFUE of approximately 65 percent.
High-Efficiency Furnace or Boiler- Special efficiency
features are incorporated to raise the AFUE above 78 percent. These
features may include an IID, forced draft systems, improved burner,
vent damper and high-efficiency heat exchanger. Other features
include: horizontal and vertical models, safety controls, quiet
operation, easy access, low emission burners, and long life heat
exchangers.
Pulse Combustion Boiler or Furnace- Rather than at a burner,
the combustion process takes place in a sealed chamber. The
ignition of gas and air takes place at a rate of about 50 to 70
times per second and results in hot gases being forced into a heat
exchanger which heats water or air. Combustion air comes from
outside the home, and the low-temperature flue gases are vented
directly outside through a small plastic pipe. A drain removes the
moisture resulting from the extraction of heat by condensing water
vapor. AFUE's of over 90 percent are achieved with this innovative
design.
Heat Pipe High-Efficiency Furnace- The heat exchanger is a
sealed tube containing a fluid. When heated, the vaporized fluid
rises and carries heat to the other end of the heat pipe. The
furnace's blower transfers this heat into the air that warms your
home. When vapor cools, it condenses and returns to the lower end
of heat pipe and cycle is repeated.
Condensing Furnace- A recuperative heat exchanger is added
to condense the water vapor in the hot flue gases and extract heat.
This raises the AFUE to over 90 percent. The condensed water is
disposed of through a drain.
Heat Transfer Module (HTM) and
Water Heating System- A module heats and distributes a
glycol/distilled water solution that is transported to the indoor
air duct system, where it heats the air that is ducted to the
house. When the temperature of the water in the water heater drops
below the preset temperature, the hot solution is automatically
diverted to a heat exchanger coil in the water heater to raise the
temperature of the water in the tank. This design provides and AFUE
up to 94 percent.
Combination Space/Water Heating - A new heating concept
utilizing a water heater as a single energy source which heats the
home and at the same time provides hot water. These
energy-efficient systems are designed primarily for use as a forced
air heating system, but they can also be adapted for new hydronic
baseboard installations. Conventional water heaters are most
commonly used, but direct vent water heaters may also be utilized
which allow the additional advantage of horizontal venting through
an outside wall. The water used for forced air system is piped from
the water heater to a heat exchanger. The fan in the air handling
unit blows air across the heat exchanger forcing heated air through
the ductwork into the living spaces. Hot water for domestic use is
piped separately from the water heater to kitchens, laundry rooms,
bathrooms or wherever it is needed.
Q. How can I interpret EnergyGuide labels?
A. The federal government requires that new furnaces and boilers
be tested using DOE test procedures to allow you to compare
efficiency ratings. An EnergyGuide is produced from these tests
that gives the Annual Fuel Utilization Efficiency for each unit
tested. Ask your local heating contractor for the EnergyGuide on
the models he has available. It will give you the proper
information to compare the costs of operating each type of
equipment. The following illustration is an example of an
EnergyGuide:
A.G.A. Design
Certification
When shopping for your new gas heating system, always be sure the
models you are considering are Design Certified by the American Gas
Association (in the United States), Canadian Gas Association (in
Canada) or another nationally recognized laboratory. In 1993, the
American Gas Association and Canadian Gas Association formed a
joint venture called "International Approval Services" as a means
of helping to ensure that the design of gas appliances sold in
these two countries meet appropriate national standards.
